Added Start_Of_Linked_List_Cycle.py

leetcode/October LeetCoding Challenge/Start_Of_Linked_List_Cycle.py

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+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution:
+    def detectCycle(self, head: ListNode) -> ListNode:
+        try:
+
+            slow = head.next
+            fast = head.next.next
+
+            while slow != fast:
+                slow = slow.next
+                fast = fast.next.next
+
+            else:
+                l = 1
+                temp = slow.next
+                while temp!=slow:
+                    temp = temp.next
+                    l+=1
+
+            p1 = head
+            p2 = head
+            for i in range(l):
+                p2 = p2.next
+
+            while p1!=p2:
+                p1 = p1.next
+                p2 = p2.next
+
+            return p1
+
+
+        except:
+            return None # No Cycle